Harlan Ellison's "Jeffty is Five": It appears in a lot of All Time Top 50 lists, though I cannot figure out why.

From what I recall, it's the familiar grandmother's lament on how music was music when she was young & now it's noise, or how milk was "free" when she was young (because the family had buffaloes & lived in a village) against Rs 22 a liter today in city!

Jeffty, a boy at the heart of the story, has the time magically stopped for him at age 5 while rest of the world moves on!